Friction Study
Airport operations during the winter months can be particularly susceptible to adverse surface conditions with the presence of snow, ice, and slush on the runway surface. These contaminants can reduce the ability of an aircraft to decelerate safely to a complete stop within the length of the available runway. Contaminated runway conditions can be a contributing factor to aircraft incidents and accidents, may cause potential flight delays, and can increase operating costs. Studies have been conducted by NASA, the FAA, Transport Canada and other parties, in an attempt to acquire accurate quantification of runway surface conditions so that airport operators will be aware when additional measures need to be taken to increase the level of friction to acceptable values. The FAA provides guidance on winter operations at airports through the Advisory Circular 150/5200-30B
Most of the recent historical studies have been conducted with a focus on airports that serve large transport category turbo-jet airplanes. The reality is that airports that serve both transport category operations and General Aviation operations need improved methods for determining accurate runway surface conditions. Therefore, new research and studies should include and consider this fact in order to ensure that findings are applicable to all airports.
General aviation airports that serve all facets of the aviation industry often times fall victim to the misdiagnosis of runway braking action conditions by pilots. An example of one such airfield is the Grand Forks International Airport, which is home to the University of North Dakota’s John D. Odegard School of Aerospace Sciences. JDOSAS provides flight training to all levels of flight experience with many “new” pilots providing their interpretation of current runway conditions. For instance, Air Traffic Control could request a braking action report from a small general aviation aircraft, causing a student pilot to give their opinion of the runway conditions. If that student pilot misinterprets the conditions as NIL, the airport authority will be required to conduct additional runway surface friction testing before an airliner can conduct further operations. This situation creates problems and costs money. A concern for the pilot in command (PIC) is the impossible task of attempting to interpret the MU reading and its affects regarding additional stopping distance and handling characteristics for the particular make and model of their aircraft.
The overlying predicament that needs resolution to improve the margin of safety is to convert the MU values into actual braking action distances for various types of aircraft. Even the Advisory Circular states that the friction measurement numbers should not be correlated into Good/Fair/Poor or Nil conditions and should only be used by the airport operators for a general assessment of pavement surface conditions. Without the correlation of friction measurement numbers to actual braking capability of the aircraft, the pilot has not received all of the available information regarding the safety of their flight. The focus of this study and research is to provide this additional information, allowing the PIC to better assess the current conditions and to prevent potential mishaps through the execution of proper Aeronautical Decision Making.
The University of North Dakota possesses the cutting-edge technology, qualified pilots, research personnel, and resources to effectively conduct the braking action research. With the use of two Light Detection and Ranging (LIDAR) systems, possible errors that could result from different variables (such as braking speed and exact stopping distance) can be eliminated, leading to more accurate braking action results. The University of North Dakota has access to multiple aircraft of varying types with qualified pilots to operate them. Using the same pilots to operate the aircraft during braking action testing runs will reduce the human error aspect of the study. The John D. Odegard School of Aerospace Science’s premier flight training program employs over 200 flight instructors with over 1,000 active flight students whom will help provide additional research and insight into this project.